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What was the optional gearing in a Snow Master?

Snowcat Operations

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I have been going thru my paper work and see that the Snow Master had an optional gearing option. This gearing would give the Snow Master a top speed of 18 MPH instead of the standard 14 MPH. Was it simply the 12 tooth small sprocket instead of the 11 tooth?
 

Lyndon

Bronze Member
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The small sprocket came in 11, 12, 14 and 15 tooth. The large sprockets came in 36 & 42. If you have one that's in fairly good condition a gear cutting machine shop could make you what ever size you want, .. for a price.
 

Melensdad

Jerk in a Hawaiian Shirt & SNOWCAT Moderator
Staff member
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Lyndon,
If someone was going to have new gears cut, do you know what the diameter of the gears should be for each of the tooth counts? Or would a good machine shop simply be able to figure out the diameter by calculating it from using the appropriate tooth size?
  1. What combination of small & large sprockets would yield the fastest/highest top speed?
  2. Is there any way to predict the top speed of each of the various possible configurations?
  3. If you set up a Snow Trac for higher top speed, is it reasonable to assume it will have a decreased ability to climb steep inclines?
 

Snowcat Operations

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1. Smaller front Sprocket and bigger rear sprocket. (than currentlt sized. Instead of a 42 big you have a 36 = higher top end speed but gives you a higher gear ratio so you loose low end grunt. Its a fine line to play on.

2. Math can be used to determine top speed roughly. There are alot of other considerations (if you put a bigger engine in) like engine power, Red line, ect. But a general top end speed can be figured out. I will post the formulas.

3. If it were a stock Snow Trac and you changed the gearing for High speed then yes you would loose climbing ability. If you put a much largewr and more torquey engine it it then the effects would be lessoned. Again there is a fine line. Once you go over it then you have a Snow Trac great for fast flat snowcatting.
 

Snowcat Operations

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Sorry I see now those were for Lyndon. Well thats my take at least. I figured Lyndon would have known off hand which gear size they used for the 18 MPH.
 

Lyndon

Bronze Member
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NO, But, and this is very important, the Drive Chain on a Snow Trac is NOT standard 80 ASE. Most belt and chain specialty places will make this mistake and sell you the wrong stuff. It will chip the teeth of the large sprockets. The correct chain is available from the chain suppliers here in the states. It is manufactured in Japan as well as Germany and England. From the Chain Data a Gear Place can determine the correct 'Pitch Diameter', but they will still need the old gear to determine the internal spline size. For both the small and the large sprockets the overall width needs to be exactly what it was originally manufactured at. I'm not talking about the width of the teeth. On the Variator the End Play of the axels as well as the seal depend on the overall width of the gear. Likewise on the big (36 & 42) tooth drive sprockets there is a seal surface as well as a width dimension that prevents the shaft from sliding back and forth. This should be kept to just a few thousandts. Some Snow Trac's original bearings in the Axel Housing (ST17 on old style Snow Trac, ST53 on new style Snow Trac, ST51 on New Style Snow Master, and I don't know the number for a Trac Master, but it's different that the Snow Master) had tapered roller bearings that needed to be held together and adjusted just like the front wheel bearings on an old truck or car. There is a substitute bearing that is Fixed in a race and does not require the 'End Play' adjustment which I highly recomend. Even with these one should have only a few thousandts of an inch end play or problems will develop with the seals and brakes. Also, only on old style snow trac and trac master, the bolts that hold the brass sprockets to the brakedrum will rub on the support ear of the Axel Housing and eventually grind off the ear. Drive chains should be replaced at roughly 3000 Mile intervals. Carry a spare master Linc.
 

Lyndon

Bronze Member
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Re: Ratios

Snow Trac "Stock" had 12 for the small and 36 for the large providing a ratio of 1 to 3. Stock for Trac Masters and Snow Masters was 11 at the Variator and 42 for the track spindle providing a ratio of 1 to 3.81. This supports the Hours to Miles ratios suggested by Northwest Tell of 3 to 1 and 2 to 1. That translates to 3 Miles pre Hour, and 2 Miles per Hours respectively for Snow Trac's and Master's. So far I have never seen a machine that did not substantiate this as long as the Hours Meter and Odometer were left hooked up. I tried running Snow Trac Gearing in a Trac Master that had a larger than normal engine and it still wasn't enough engine. As far as not having low enough gears, this was never a problem. Snow Trac's and all their variatons are really "SNOW TRACTORS". As previously reported elsewhere in the Forum, Stock speeds for a Snow Trac is around 20 to 22 MPH. The Masters larger heavier track picked up so much snow that it would have required 90 or 100 HP to operate at 20 MPH in loose powder.
 

Lyndon

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Re:Low Gears & Horse Power

The Machine that couldn't make it with the Snow Trac Gears had about a 75 HP Motor. Another 10 horse would have done it. 90 would definately make it. As to loosing climbing ability, I disagree with your assesment that the taller gears would impact the climbing ability because the machines are already geared so low. First and even second are so low in a snow trac that with a larger engine we found that one could climb hills and go pretty much anywhere in JUST 3rd and 4th. About the only use for the low gears was for pulling out Stuck Kristi's, Stuck Truck used to haul Kristi, or loading on to a tilt deck trailers.
 

redsqwrl

Bronze Member
GOLD Site Supporter
NO, But, and this is very important, the Drive Chain on a Snow Trac is NOT standard 80 ASE. Most belt and chain specialty places will make this mistake and sell you the wrong stuff. It will chip the teeth of the large sprockets. The correct chain is available from the chain suppliers here in the states. It is manufactured in Japan as well as Germany and England. From the Chain Data a Gear Place can determine the correct 'Pitch Diameter', but they will still need the old gear to determine the internal spline size. For both the small and the large sprockets the overall width needs to be exactly what it was originally manufactured at. I'm not talking about the width of the teeth. On the Variator the End Play of the axels as well as the seal depend on the overall width of the gear. Likewise on the big (36 & 42) tooth drive sprockets there is a seal surface as well as a width dimension that prevents the shaft from sliding back and forth. This should be kept to just a few thousandts. Some Snow Trac's original bearings in the Axel Housing (ST17 on old style Snow Trac, ST53 on new style Snow Trac, ST51 on New Style Snow Master, and I don't know the number for a Trac Master, but it's different that the Snow Master) had tapered roller bearings that needed to be held together and adjusted just like the front wheel bearings on an old truck or car. There is a substitute bearing that is Fixed in a race and does not require the 'End Play' adjustment which I highly recomend. Even with these one should have only a few thousandts of an inch end play or problems will develop with the seals and brakes. Also, only on old style snow trac and trac master, the bolts that hold the brass sprockets to the brakedrum will rub on the support ear of the Axel Housing and eventually grind off the ear. Drive chains should be replaced at roughly 3000 Mile intervals. Carry a spare master Linc.


I was readiing Louis' build where he regeared his snow trac to a 16 tooth variator chain sprocket. He used a 80-16T sprocket. In Lyndons quote above he states the chain is not a ASE 80. Does anyone know the trade name of the chain size.?

Good day mike.
 

JimVT

Bronze Member
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my chain has czechoslovakia on every link. and my spare links have ISO 168
 

redsqwrl

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Very helpful.

Actually it is 16 B

ISOtable33bf40c87db8428ea4b5c4cfcd786c79.png
 

redsqwrl

Bronze Member
GOLD Site Supporter
same as ASE 80.

Anyone have the variator output shaft size and spline count?
Said another way the sprocket hub?

trying to get a jump start on a double sprocket idea. Got a box of ASE 80 sprockets today.
 

Lyndon

Bronze Member
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The chain is a standard metric size that is very close to 80B SAE. BUT, 80B SAE will chip the large sprockets and cause excessive weear on both sprockets.
 

redsqwrl

Bronze Member
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I Can't find the edit button?

When I went down to the millwrights and inquired about the metric chain he looked down his nose, cleared his throat and with all the knuckle dragging body language he could muster he proceded to inform me that my measure (three pins and then divide by two) math was unnecessary..... that all chain is either by 1/8s ASE or by 16ths Metric. From WIKI I found this "Metric pitches are expressed in sixteenths of an inch; thus a metric #8 chain (08B-1) would be equivalent to an ANSI #40"

ISO 16 B 16 1/16ths
ASE 8 0 8 1/8ths have rollers that are both 15.88...

Armed with his input and Louis in quebec installing a 80-16 I ordered a bucket-o-sprockets....

I intend to run the ST chain and big sprocket that are there now, I am changing the lower sprockets, Hopefully I don't cause a harmonic or friction situation that eat up some component or another?

I am fresh out of unobtainium.....

Help?
 

Snowtrac Nome

member formerly known as dds
GOLD Site Supporter
i have no clue what gearing i'm running but i can only get 16 mph at 4500 rpm now i have the 1776 i'm thinking about stepping up the gear ratio even with the extra horse power i find my self down to second gear in places trying to cloimb anvil mountain
 

Cidertom

Chionophile
GOLD Site Supporter
pitch roller diameter
80 1.000 in (25.40 mm) 0.625 in (15.88 mm)


ASE 80 is dimensionally the same as ISO 16B is there another standard (metric) that I am not finding?

Sort of... There is one difference that is not being mentioned in this thread. ASE80 width is 0.627 16B width is 0.670
So ASE 80 is 0.043 narrower. While this doesn't sound like much, it certainly could account for damage as the chain links would be rubbing at the sprockets more than designed.

My $0.02
Tom
 

300 H and H

Bronze Member
GOLD Site Supporter
Sort of... There is one difference that is not being mentioned in this thread. ASE80 width is 0.627 16B width is 0.670
So ASE 80 is 0.043 narrower. While this doesn't sound like much, it certainly could account for damage as the chain links would be rubbing at the sprockets more than designed.

My $0.02
Tom


I think your onto something here.....Maybe take 0.022 from each side of all the sprockets in the lathe, and run either one, metric or English.

What do you think of this idea?

Regards, Kirk
 

Cidertom

Chionophile
GOLD Site Supporter
And for what it's worth: "metric" roller chains are actually "British Standard" . The same folks that gave us "BSP" (British Standard Pipe) and the Wentworth Thread system. With Wentworth many are the same problem we have with the chains. Close enough that it seems to work, but not really correct.

I think that sums up the Snow Track a mixture of metric, english and rounded off. Determined by the wrench you didn't grab.
 

300 H and H

Bronze Member
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Wentworth?

I remeber an english gent, and engineer name Whitworth. He was responcilbe for making the Whitworth rifle under orders from the Queen.. He is also the guy who discoverd that to make a truely flat parralel piece it takes three others to lap it dead flat. Also I thought he was responcible for their english "Whitworth threads" Or am I mistaken and this is some one else??

Regards, Kirk
 

Cidertom

Chionophile
GOLD Site Supporter
Wentworth?

I remeber an english gent, and engineer name Whitworth. Also I thought he was responcible for their english "Whitworth threads" Or am I mistaken and this is some one else??

Regards, Kirk


Nope, I'm certain you are correct. I was going from clouded long term memory. I know I have seen it both ways, but Whitworth is the most common usage. My bad.

Tom
 

redsqwrl

Bronze Member
GOLD Site Supporter
25.4 - 17 is the OEM chain on the STrac. assuming I still have that chain installed......

I am intending to replace a Sprocket. (at the variator output)

I think I will be fine. I think this because If I understand all the input here, the new 80 Sprockets will be of the ASE (narrower) thickness.

If my chain is not OEM and has been changed to the 16B or 80 chain then I will narrow up the Sprockets a bit, (pronounced Grind them in a lathe)

Thanks for the input. I will again start moving forward.

Mike
 

300 H and H

Bronze Member
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(pronounced Grind them in a lathe)

Not the thing to do Mike, use the cutters to cut it off. Grinding is not what you want to do in a good lathe. Cutting it, or facing the sides would be faster too....

Just ribbin ya's :wink:

Kirk
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
I think your onto something here.....Maybe take 0.022 from each side of all the sprockets in the lathe, and run either one, metric or English.

What do you think of this idea?

Regards, Kirk
I would worry about taking the hard surface off the sprocket. That surface is made to be harder than the chain so you can replace the chain and not the sprocket.
 
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